The present invention generally relates to stabilized and strengthened metals and, more specifically, to metals stabilized and strengthened, especially at high temperatures, by the addition of diamondoid.
Nano crystalline materials are defined as single or multi-phase polycrystals with grain size less than 100 nm in at least one dimension. Considerable recent evidence has indicated that nanocrystalline alloys may provide mechanical and electrical properties superior to those of their coarse-grained counterparts. (C. Suryanarayana: Int. Mater. Rev., 1995, vol. 40, pp. 41-64. M. Gell: Mater.Sci.Eng., 1995, vol.A204, pp. 246-51. H. Gleiter: Nanostruct. Mater., 1992, vol. 1, pp. 1-19.) This potential superiority results from the reduced dimensionality of nanometer-sized crystallite as well as from the numerous interfaces between adjacent crystallite. (H. Gleiter: Nanostruct. Mater., 1992, vol. 1, pp. 1-19.) A number of processing techniques are currently available to produce nc materials including inert gas condensation (R. Birringer, H. Gleiter, H. P. Kelien, and P. Marquardt: Phys. Lett., 1984, vol. A102, pp. 356-60.), rapid solidification (A. Inoue: Mater.Sci.Eng. A, 1994, vols. 179-180, pp. 57-61.), electro-deposition (G. D. Hughes, S. D. Smith, C. S. Pande, H. R. Johnson and R. W. Armstrong: Scripta Metall., 1986, vol. 20, pp. 93-97.), sputtering (Z. G. Li and D. J. Smith: Appl.Phys.Lett., 1989, vol. 55, pp. 919-23.), crystallization of amorphous phases (K. Lu and J. T. Wang: J.Appl Phys., 1991, vol. 69, pp 522-31.), laser ablation (M. L. Mandich, V. E, Bondybey and W. D. Reents: J. Chem. Phys., 1987, vol. 86, pp. 4245-55.), chemical processing (V. M. Segal, V. I. Reznikov, A. E. Drobyshevskiy and V. I. Kopylov: Metally., 1981, Vol. 1, pp. 11523.). Comparison of these methods in terms of cost and productivity demonstrates that ball milling is the most cost effective route capable of producing nc materials in large quantity. During the milling process, extreme cyclic deformation is induced in the powders as they undergo repeated welding, fracturing and rewelding. Thus, the resulting nanostructure is produced by structural decomposition of coarse grains as the result of severe plastic deformation. (H. J. Fecht: Nano-Struct. Mater., 1995, vol. 6, pp. 33-42.)
Rapid and extensive grain growth generally occurs during elevated temperature consolidation of cryomilled powders undermining the significant progress that has been achieved in the synthesis of nanocrystalline precursors. Nanoscale grains tend to be highly unstable in this regard. For example, the Gibbs-Thomson equation (P. G. Shewmom: Transformation in Metals, McGraw-Hill, New York, 1969, pp. 300.) predicts that the driving force for grain growth increases substantially with decreasing grain size to the nanoscale. Accordingly, recent studies have investigated ways in which the thermal stability of nanocrystalline microstructure might be enhanced. For example, added thermal stability for cryomilled nanostructures is attributed to the pinning of grain boundaries by a dispersion of second-phase Al2O3, AlN and Al4C3 particles. (R. J. Perez, H. G. Jiang, C. P. Dogan and E. J. Layernia: Met. & Mat. Trans.A., 1998, vol 29A, pp. 2469-75. F. Zhou, J. Lee, S. Dallek, and E. J. Layernia: J. Mater.Res., 2001, vol. 16, pp. 3451-58.) These dispersions are incoherent nanoscale second-phase particles, highly stable at high temperatures and insoluble in matrix. At elevated temperature, they favorably segregate to the grain boundaries and act as an effective barrier (dispersion strengthening) to the movement of grain boundaries. (I. Roy, M. Chauhan, E. J. Layernia, F. A. Mohamed: Met & Mat Trans A., 2006, vol 37A, 721-30. J. E. Burke: Trans.TMS-AIME, 1949, vol. 180, pp. 73-79.)
As can be seen, there is a need for improved stabilized metals, especially for metals made from nano crystalline materials which may be stabilized at high temperatures.